Sources of Infection and Risk Factors

Dad changing diaper

Shigella germs spread easily from one person to another and it only takes a small amount to make someone sick with a disease called shigellosis. Learn how Shigella germs spread and why some people have a greater chance of getting infected.

Did You Know? People with Shigella infection (shigellosis) can shed (get rid of) the bacteria in their stool (poop) for up to two weeks after symptoms have gone away. If you or someone you know has or recently had diarrhea, be sure to take steps to help prevent the spread of disease.

People can get Shigella infection by:

  • Getting Shigella germs on their hands and then touching their food or mouth. This can happen after:
    • Changing the diaper of a sick child or caring for a sick person.
    • Touching surfaces contaminated with germs from poop from a sick person. Surfaces include diaper pails, changing tables, bathroom fixtures, and toys.
  • Eating food that was prepared by someone who has a Shigella infection (shigellosis).
    • Foods that are consumed raw are more likely to be contaminated with Shigella germs.
    • Shigella germs can also get on fruits and vegetables if the fields where they grow are contaminated with poop containing the germ.
  • Swallowing recreational water (for example, lake or river water) while swimming or drinking water that is contaminated with poop containing the germ.
  • Having contact with poop during sexual contact with someone who has or recently had diarrhea.

Groups of People Who Are Most Likely to Get Sick

  • Shigella infection (shigellosis) is most common among young children. Children can get infected if they put unwashed hands in their mouth after touching something that is contaminated with Shigella germs. These germs can spread easily among children and to family members and others in the community. In fact, many outbreaks occur in settings such as childcare and school.
  • Travelers to countries that do not have treated tap water or adequate sanitation may be more likely to get shigellosis, and to become infected with strains of Shigella germs that can’t be treated effectively by antibiotics.2,3 Travelers may get sick from food, drinking water, recreational water, and surfaces containing Shigella germs. Travelers can protect themselves by sticking to safe eating and drinking habits, and washing hands often with soap and water or using hand sanitizer with at least 60% alcohol if soap and water are not available.
  • Gay or bisexual men and other men who have sex with men* are more likely to get Shigella infection (shigellosis) than other adults.4 Shigella germs pass from the poop or soiled fingers of one person to the mouth of another person, which can happen during sexual activity. Many shigellosis outbreaks among gay and bisexual men have been reported worldwide.5-12 For more information, see Shigella Infection Among Gay, Bisexual, and Other Men Who Have Sex with Men (MSM).
  • People whose immune systems are weakened due to illness (such as HIV) or medical treatment (such as chemotherapy for cancer) can get a more serious illness. A severe shigellosis illness may involve the infection spreading into the blood, which can be life-threatening.13
  • Large outbreaks of shigellosis often start in childcare settings and spread among small social groups.14-16
  • Outbreaks can occur among any race, ethnicity, or community social circle because Shigella germs spread easily from one person to another.

*The term “men who have sex with men” is used in CDC surveillance systems because it indicates men who engage in behaviors that may transmit Shigella infection, rather than how someone identifies their sexuality.

  1. Adams DA, Jajosky RA, Ajani U, Kriseman J, Sharp P, Onwen DH, Schley AW, Anderson WJ, Grigoryan A, Aranas AE, Wodajo MS, Abellera JP. Summary of notifiable diseases–United States, 2012. MMWR Morb Mortal Wkly Rep. 2014;61(53):1-121.
  2. Kantele A. As far as travelers’ risk of acquiring resistant intestinal microbes is considered, no antibiotics (absorbable or nonabsorbable) are safe.external icon Clin Infect Dis. 2015;60(12):1872-1873.
  3. O’Donnell AT, Vieira AR, Huang JY, Whichard J, Cole D, Karp BE. Quinolone-resistant Salmonella enterica serotype Enteritidis infections associated with international travel.external icon Clin Infect Dis. 2014;59(9):e139-41
  4. Aragon TJ, Vugia DJ, Shallow S, Samuel MC, Reingold A, Angulo FJ, Bradford WZ. Case-control study of shigellosis in San Francisco: the role of sexual transmission and HIV infection.external icon Clin Infect Dis. 2007;44(3):327-34.
  5. Heiman KE, Karlsson M, Grass J, Howie B, Kirkcaldy RD, Mahon B, Brooks JT, Bowen A. Notes from the field: Shigella with decreased susceptibility to azithromycin among men who have sex with men – United States, 2002-2013. MMWR Morb Mortal Wkly Rep. 2014;63(6):132-3.
  6. Worley JN, Javkar K, Hoffmann M, Hysell K, Garcia-Williams A, Tagg K, Kanjilal S, Strain E, Pop M, Allard M, Francois Watkins L, Bry L. Genomic drivers of multidrug-resistant shigella affecting vulnerable patient populations in the United States and abroadexternal icon. mBio. 2021 Jan 26;12(1):e03188-20. doi: 10.1128/mBio.03188-20.
  7. Bardsley M, Jenkins C, Mitchell HD, Mikhail AFW, Baker KS, Foster K, Hughes G, Dallman TJ. Persistent transmission of Shigellosis in England is associated with a recently emerged multidrug-resistant strain of Shigella sonneiexternal icon. J Clin Microbiol. 2020 Mar 25;58(4):e01692-19. doi: 10.1128/JCM.01692-19.
  8. Newman KL, Newman GS, Cybulski RJ, Fang FC. Gastroenteritis in Men Who Have Sex With Men in Seattle, Washington, 2017-2018. Clin Infect Dis. 2020 Jun 24;71(1):109-115. doi: 10.1093/cid/ciz783.
  9. Morgan O, Crook P, Cheasty T, Jiggle B, Giraudon I, Hughes H, Jones SM. Shigella sonnei outbreak among homosexual men, London. Emerg Infect Dis. 2006;12(9):1458-60.
  10. Okame M, Adachi E, Sato H, Shimizu S, Kikuchi T, Miyazaki N, Koga M, Nakamura H, Suzuki M, Oyaizu N, Fujii T, Iwamoto A, Koibuchi T. Shigella sonnei outbreak among men who have sex with men in Tokyo.external icon Jpn J Infect Dis. 2012;65(3):277-8.
  11. Watson, JT, Jones RC, Fernandez J, Cortes C, Gerber SI, Kuo KJ, Price JS, Brooks JT, Jennings D, Fair M, Mintz E, Bowen A. Shigella flexneri serotype 3 infections among men who have sex with men–Chicago, Illinois, 2003-2004. pdf icon[PDF – 24 pages] MMWR Morb Mortal Wkly Rep. 2005;54(33):820-2.
  12. Bowen A, Eikmeier D, Talley P, Siston A, Smith S, Hurd J, Smith K, Leano F, Bicknese A, Norton C, Campbell D. Notes from the Field: Outbreaks of Shigella sonnei infection with decreased susceptibility to azithromycin among men who have sex with men — Chicago and Metropolitan Minneapolis-St. Paul, 2014. MMWR Morb Mortal Wkly Rep. 2015;64(21):597-8.
  13. HHS. Guidelines for the prevention and treatment of opportunistic infections in HIV-infected adults and adolescents: recommendations from the Centers for Disease Control and Prevention, the National Institutes of Health, and the HIV Medicine Association of the Infectious Diseases Society of America. pdf icon[PDF – 509 pages]external icon Panel on Opportunistic Infections in HIV-Infected Adults and Adolescents. 2015.
  14. De Schrijver K, Bertrand S, Gutierrez Garitano I, Van den Branden D, Van Schaeren J. Outbreak of Shigella sonnei infections in the Orthodox Jewish community of Antwerp, Belgium, April to August 2008.external icon Euro Surveill. 2011;16(14).
  15. Garrett V, Bornschlegel K, Lange D, Reddy V, Kornstein L, Kornblum J, Agasan A, Hoekstra M, Layton M, Sobel J. A recurring outbreak of Shigella sonnei among traditionally observant Jewish children in New York City: the risks of daycare and household transmission.external icon Epidemiol Infect. 2006;134(6):1231-6.
  16. Sobel J, Cameron DN, Ismail J, Strockbine N, Williams M, Diaz PS, Westley B, Rittmann M, DiCristina J, Ragazzoni H, Tauxe RV, Mintz ED. A prolonged outbreak of Shigella sonnei infections in traditionally observant Jewish communities in North America caused by a molecularly distinct bacterial subtype.external icon J Infect Dis. 1998;177(5):1405-9.